1. Field of the Invention
The present invention relates to a semiconductor inspection apparatus and a semiconductor inspection method and, more particularly, relates to a method for adjusting an imaging magnification of an inspection apparatus which takes an image of a structure on a semiconductor wafer and analyzes it.
2. Description of the Related Art
A charged particle beam apparatus such as a scanning electron microscope is a device suitable for measuring and observing patterns formed on a semiconductor wafer whose miniaturization has been advancing. In the case where the patterns formed on the semiconductor wafer are measured or observed, inspection by the charged particle beam apparatus is automatically and continuously performed. However, imaging conditions, image processing conditions, and inspection conditions such as inspection items, which are for observing and measuring, need to be manually set by an operator. For example, a measurement magnification for a measurement point or a length measurement point is judged and determined by the operator so that a pattern is entered in a field of view and a range for length measuring can be specified. In such a method, however, all of the measurement points or the length measurement points in a recipe need to be checked and determined one by one by the operator.
On the other hand, Japanese Patent Application Laid-Open No. 5-102259 discloses a secondary electron image magnification setting means for setting a secondary electron image magnification into an electron beam device so that the number of wirings n in a region corresponding to a field of view of the secondary electron image falls in a certain range on the basis of design data of wiring patterns.
Japanese Patent Application Laid-Open No. 2004-95657 discloses that it is possible to estimate an inspection object size and determine a magnification for photographing the inspection object by specifying an inspection position and an inspection item by means of design data.
In the Cited Document 1, the magnification is calculated by the number of wirings included in a layout drawing based on the design data. However, in a situation where recent design data is complicated, wirings which can be counted up are not necessarily present at a place to be desirably measured. Furthermore, the magnification is determined so that the number of wirings n falls within a range of n1≦n≦n2 in determining the magnification; however, there is not disclosed how n1 and n2 are determined.
In the Cited Document 2, the imaging magnification cannot be specified unless a line width, a space width, a pitch width, and the like are preliminarily specified as inspection items. In such a method, it is very troublesome because pattern shapes (line, hole, and the like) and measurement portions (line width, hole size, and the like) to be measured need to be preliminarily set with respect to very many inspection positions.